Flake8 omero/util

This PR fixes the flake8 warnings from `omero/util`

One external file has been moved untouched to `omero_ext`. Three files have been removed, these are all: unimported by anything and: have no main method, are clearly old or are clearly broken.

Travis and Jenkins should both pass.


This seems weird. Not sure why we would be doing this if we're not using it.